Plant extraction method

A plant extraction method comprising the following steps of:

• step 1):
• preparing a crude plant extraction solution by using a plant raw material;
• and concentrating the crude plant extraction solution;
• step 2):
• separating the concentrated crude extraction solution via a cation resin and an anion resin to obtain a collection solution;
• wherein:
• the cation resin is one or a combination of more selected from a strongly acidic cation exchange resin, a weakly acidic cation exchange resin, and a strongly alkaline quaternary ammonium-type cation resin;
• the amount of the cation resin used and the plant raw material have a weight ratio ranging from 1:1 to 1:30;
• an eluent for the cation resin is a salt solution containing cations or an alkaline solution containing cations;
• and the cations in the eluent have a concentration ranging from 0.04 to 5 mol/L;
• collection from the cation resin begins when the pH of the effluent is higher than 7 or the starting point of the collection of the effluent is determined according to properties of components to be separated as determined by utilizing a precipitation reaction;
• and the collection from the cation resin is terminated when the volume of the collection solution reaches 0.1 to 10 times the weight of the plant raw material;
• a weight of the eluent used for the separation via the cation resin is 0.1 to 30 times the weight of the plant raw material;
• the anion resin is one or a combination of more selected from a strongly alkaline anion exchange resin, a weakly alkaline anion exchange resin, and a weakly acidic anion exchange resin;
• and
• the amount of the anion resin used and the plant raw material have a weight ratio ranging from 1:1 to 1:80;
• collection from the anion resin is terminated when the volume of the collection solution reaches 0.05 to 10 times the weight of the plant raw material;
• step 3):
• concentrating the collection solution obtained in step 2);
• step 4):
• subjecting the concentrated solution obtained in step 3) to alcohol precipitation using ethanol as the alcohol, wherein the ethanol used for the alcohol precipitation and the plant raw material have a weight ratio ranging from 1:4 to 1:600;
• and
• optionally, step 5):
• concentrating and drying,
• wherein
• the plant is a branch of a plant selected from the group consisting of Hyacinthus orientalis, Adenophora Triphylla var. japonica, and Commelina communis;
• a plant extract obtained by the plant extraction method contains each component in the following weight ratios with respect to a total weight of the plant extract:
• alkaloids 30% to 99%;
• polysaccharides 0.2% to 35%;
• flavones 0.05% to 2%;
• amino acids 0% to 25%;
• and other components 0% to 20%;
• the alkaloids in the plant extract contain 1-deoxynojirimycin with a weight content of 50% to 99% with respect to a total weight of the alkaloids, and
• the heavy metal content of the plant extract is not more than 10 ppm.